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Scientists have thought that if planetary warming could be kept below a 2-degree Celsius increase, perils such as catastrophic sea-level rise and searing heat waves could be avoided.

Ongoing data, however, indicate that three global feedback mechanisms may be pushing Earth into a period of rapid climate change even before the 2-degree C "limit" is reached: Ice melting into the oceans, which warms surface seawater, leading to more melting; thawing of permafrost, which releases carbon dioxide and methane into the atmosphere, raising the air temperature and melting more permafrost; and glaciers breaking up and falling into the sea, which lessens the amount of sunlight reflected into space, thereby heating the atmosphere and further degrading glaciers.

The feedbacks could ultimately alter weather by changing the jet stream's path, magnify insect infestations and spawn more and larger wildfires.